Protozoa Flashcards
Virulence factor of E. histolytica that causes flask-shaped colonic ulcerations
Cysteine proteases
Diagnostic stage of E. histolytica, Giardia lamblia
- Trophozoites if diarrhea, 2. Cysts if stool is formed
Most common extraintestinal E. histolytica infection; produces and anchovy paste-like aspirate
Amoebic liver abscess
Tx for amoebic cyst carrier state
Diloxanide furoate
Tx for symptomatic amoebic disease (colitis, liver abscess)
Metronidazole
Flagellate with a “grandfather’s face” morphology and falling leaf motility; causes malabsorption, foul smelling flatus, and steatorrhea, and is the most common cause of backpacker’s diarrhea (drinking water from open sources)
Giardia lamblia
Most common cause of severe diarrhea in AIDS patients (CD4
Cryptosporidium parvum
Only exists as a pear shaped trophozoite; causes foul smelling, greenish frothy vaginal discharge, strawberry cervix
Trichomonas vaginalis
DOC for cryptosporidium parvum
Nitazoxanide
DOC for trichomonas vaginalis
Metronidazole
DOC for giardia lamblia
Metronidazole
Asexual life cycle (schizogony and gametogony) of plasmodium
Man (intermediate host)
Sexual life cycle (sporogony) of plasmodium
Mosquito (definitive host)
Vector of disease in malaria
Anopheles flavirostris minimus
Schizonts in these strains can remain dormant and become reactivated as hypnozoites; causes recurrence (return after apparent cessation)
P. ovale and P. vivax
Schizonts in the blood
Merozoites
Confers immunity against malaria
RBC defects (G6PD, sickle cell anemia, thalassemia)
Premonition (partial immunity) seen in individuals who recover from __________ malaria
P. falciparum
All strains of malaria present with tertian fever except
P. malariae (quartan)
Prefers old RBCs
P. malariae
Highest parasitemia, banana shaped gametocytes, cerebral malaria, drug resistance
P. falciparum
Recrudescence (recurrence after a temporary abatement) occurs in:
P. falciparum and P. malariae
Screens for presence of plasmodium organisms
Thick smear
Confirms and identifies plasmodium species
Thin smear
Schuffner dots: punctate granulations in RBCs
P. ovale, P. vivax
Maurer dots: coarse granulations
P. falciparum
Ziemann dots: fine dots
P. malariae
Durck granulomas
Cerebral malaria
Acute renal failure in P. falciparum malaria
Blackwater fever
Areas of high malaria endemicity (4)
- Palawan
- Kalinga-Apayao
- Ifugao
- Agusan del Sur
Areas of chloroquine resistance (3)
- Palawan
- Davao del Norte
- Compostela valley
Treatment for P. falciparum and P. malariae infections
Chloroquine
Treatment for P. vivax and P. ovale infections
Chloroquine + primaquine (to eradicate hypnozoites)
Treatment of malaria in pregnant women
Quinidine or quinine
Prophylaxis of malaria in pregnant women
Mefloquine
Malaria prophylaxis
Doxycycline, malarone
Consists of tachyzoites (rapidly dividing) and bradyzoites (slowly multiplying, diagnostic stage); causes heterophil-negative mononucleosis or encephalitis with ring-enhancing lesions
Toxoplasma gondii
Hydrocephalus, chorioretinitis, hepatosplenomegaly, intracranial calcifications, abortion or stillbirth
Congenital toxoplasmosis
DOC for toxoplasmosis
Sulfadiazine + pyrimethamine
Transmitted by the reduviid (triatoma) bug; exists in 4 forms: metacyclic trypomastigote (infective stage) –> trypomastigote (diagnostic stage) –> amastigote (in infected tissues) –> epimastigote (in the reduviid bug)
Trypanosoma cruzi
Diagnosed with BMA, muscle biopsy, or xenodiagnosis (allowing a bug to take a bloodmeal from the patient)
Trypanosoma cruzi
Periorbital edema (Romana’s sign), nodules near bites (chagomas), myocarditis, megacolon, achalasia
Chagas disease
DOC for Chagas disease
Nifurtimox
Transmitted by the tsetse fly; cyclical fever spike every 2 weeks due to remarkable antigenic variation; can cross the blood brain barrier and cause a demyelinating encephalitis of the ARAS and brainstem
African sleeping sickness (Trypanosoma brucei)
More rapid and fatal trypanosoma brucei
Trypanosoma brucei rhodesiense
East Africa
Trypanosoma brucei rhodesiense
West Africa
Trypanosoma brucei gambiense
Enlargement of the posterior cervical LNs in African sleeping sickness
Winterbottom’s sign
Hyperesthesia in African sleeping sickness
Kerandel’s sign
Due to disruption of saltatory AP conduction in neurons
Plasma cells with cytoplasmic Ig globules in African sleeping sickness
Mott cells
Tx in West African sleeping sickness
Pentamidine (early), Eflornithine (CNS involvement)
Tx in East African sleeping sickness
Suramin (early), Melarsoprol (CNS involvement)
Most common dinoflagellate causing Red Tide in the Philippines
Pyrodinium bahamense var. compressum
Shellfish poisoning: generalized paralysis
Saxitoxin
Shellfish poisoning: stroke-like lesions
Brevetoxin
Shellfish poisoning: diarrhea
Okadaic acid
Shellfish poisoning: amnesia
Domoic acid
Granulomatous amebic encephalitis, amoebic keratitis in contact lens wearers
Acanthamoeba castellanii
Primary amebic meningoencephalitis; contracted intranasally when swimming in contaminated pools or open water
Naegleria fowleri
Only ciliated protozoan to cause human disease; cause round based, wide necked intestinal ulcers
Balantidium coli
Transmitted by the Ixodes tick; intraerythrocytic ring shaped trophozoites in the form of a Maltese cross
Babesia microti
Kala-azar
Leishmania donovani
Transmitted by the sand fly; manifests as cutaneous, mucocutaneous or visceral disease; treated with antimony compounds
Leishmania spp.
Diarrhea in immunocompromised patients (2)
Cyclospora cayetanensis, Isospora belli
